I have a 1999 mazda 626 and I have problems with it recently when the weather is getting warm. when the engine is cold, I can start the car with no problems. But when I drove the car for 15 or more minutes and the car is getting hot, problem comes. the engine suddenly quit once when I stopped in traffice light, once when I shift in parking, once when I slowed my speed. After the car quit, I tried to estart the car, it crank and did not start. The strange thing is: when I wait for 20 or more minutes, I can start the car and drive away with no problems. The machanic cannot find the casue since he cannot reproduce it. He checked the spark plog and replace the fuel filter. That did not resolve the problem.

Anyone encouter such problems previously? Any help will be welcomed and greatly appreciated.